The most common tumor is osteosarcoma which has a very high spread rate

Chondrosarcoma has a good prognosis with greater than 50% of patients cured with surgery alone

Removal of a section of the chest wall is the treatment of choice in most cases

What is it?

• In general, rib tumors are relatively uncommon in dogs and rare in cats
• Types
  • Osteosarcoma
    • The most common type of rib tumor
    • very malignant tumor
    • has a rapid spread rate (metastatic)
  • Chondrosarcoma
    • second most common tumor
    • has a much lower metastatic potential
  • Other types
    • fibrosarcoma - locally invasive and metastatic rate depends on the grade of the tumor
    • hemangiosarcoma - highly metastatic tumor

Anatomy

• Dogs have 13 ribs that form the rib cage
• Ribs attach onto the breastbone and the backbones
• Vital structures such as the heart and the lungs are protected by the rib cage
  

Signs

• Signalment
  • predisposed breeds - Golden Retrievers, mix breeds, Labrador Retrievers, Basset Hounds, Dobermans, Australian Shepherds, British Bulldog, German Short-haired Pointer, Rough coated Collie, Irish Setter, Giant Pyrenees, Rottweiler, Giant Schnauzer, Shar Pei, and Springer Spaniel
  • age - bimodal distribution with affected dogs being either young (2 to 4.5 years) or older (7 to 9 years)
• Signs owners see
  • visible or palpable mass on the side of the chest
  • lameness of the forelimb - if the tumor is located within one of the first four ribs, is compressing the nerves to the limb, is causing mechanical interference with movement of the limb or is invading into the muscles of the forelimb
  • Labored breathing may be noted if the tumor is very large and is causing collapse of the lung.
• Signs of metastasis to the lungs or chest cavity
  • labored breathing
  • weight loss
  • poor appetite

Diagnosis

• X-rays of ribs
  • The diagnosis of a rib tumor is commonly made on x-rays
  • tumor will cause a portion of the rib bone to be dissolved away
• Chest x-rays should be made to rule out visible spread of the tumor to the lungs
• A CT scan
  • provides a better evaluation of the extent of the disease and is more sensitive to detect evidence of spread of the tumor into the lungs
• Fine needle biopsy
  • may be helpful to diagnose a rib tumor, but frequently will not ascertain the specific type of tumor that is present. Usually the entire tumor is submitted for biopsy after surgery is preformed to establish a final diagnosis.
• Whole body nuclear bone scan
  • is recommended prior to surgery, as roughly 16%, of the rib osteosarcomas will have spread to other bones at the time of diagnosis.
• Preoperative blood work
  • recommended to ensure that your pet is healthy to under go anesthesia and surgery
  • complete blood count
  • chemistry profile
  • urine testing

Treatment

• Surgery
  • Minimum of 3 ribs are removed: affected rib, normal rib in front of the tumor and one rib behind the tumor
  • Lung beneath the tumor is removed if the tumor is attached to the lung
  • following removal of the tumor, the chest wall is reconstructed with either a muscle flap or a plastic mesh patch
  • a chest tube may be kept in place for 3 to 5 days
  • advanced methods of pain management are used
  • intravenous fluid are administered to maintain patient hydration
  • oxygen therapy may be administered if needed
• Chemotherapy
  • indicated for osteosarcoma
  • typically one treatment is administered every 2 to 3 weeks for a total of 5 to 6 treatments

Prognosis

• Osteosarcoma
  • local recurrence is as high as 25%, especially if the surgical margins are dirty (have tumor cells left behind)
  • Elevation of the Alkaline phosphatase enzyme level on chemistry profile is associated with a lower median survival time (210 days versus 675 days)
  • Chemotherapy will significantly increase the survival of dogs with rib osteosarcoma from a few months to about 9.5 months
• Chondrosarcomas
  • 50% chance to be cured with surgery alone
  • median survival times more than 3 years.
  • alkaline phosphatase enzyme level does not worsen the prognosis
  • grade of tumor does not affect prognosis
• Hemangiosarcoma
  • carries a very poor prognosis regardless of treatment

Homecare

• Pain control medications will be prescribed to keep your companion comfortable
• Antibiotics may or may not be prescribed
• Check the incision for signs of infection
• Put an Elizabethan collar on the patient to prevent licking of the incision
• Chest is bandaged for about 2 weeks
• Watch for breathing difficulty - respiratory rate should be less than 40/minute
• Exercise is restricted for 6 weeks

References

1. Liptak JM, Kamstock, DA, Dernell WS, et al. Oncologic outcome after curative-intent treatment in 39 dogs with primary chest wall tumors (1992-2005). Vet Surgery 37:488-496, 2008.

2. Liptak, JM, Dernell S, Rizzo SA, et al. Reconstruction of chest wall defects after rib tumor resection: a comparison of autogenous, prosthetic and composite technique in 44 dogs. Vet. Surg 37:479-487, 2008.

3. Baines SJ, Lewis S, and White RAS. Vet Record 16:335-339, 2002.

4. Matthiesen DT, Clark GN, Orsher RJ, et al. En bloc rib resection of primary rib tumors in 40 dogs. Vet Surg 21:201-20, 1992.